Precision measuring instrument having a thread for a motion transmission link



y 3, 1949- w, WHITEHEAD 2,468,906

PRECISION MEASURING INSTRUMENT HAVING A THREAD FOR A MOTION TRANSMISSION LINK Filed Jan. 4, 1945 INVENTOR.

WILLIAM WHITE HEAD ATTORNEYS Patented May 3, 1949 PRECISION MEASURING INSTRUMENTHAV- .ING A THREAD FOR A MOTION TRAN SMIS- SION LINK illiam Whitehead, Forest Hills; N. Y., assignor to Celanese Corporation of America, a corpora- .tion-ofi Delaware Application January 4, 1945; Serial 'N0. -571,236

4 Claims. 1

'..'I?histinvention rclates'to mechanical devices, .zsuch: as, for example instruments employedior .smeasuring and/or recording purposes, and relates :more. particularly to improved-mechanical devices containing. as an essential element thereof threads ofsubstantial dimensionalstability.

objectofthisrinvention is the provision of mechanical devices ofincreased accuracyas; for zexani'ple, :rzmeasuring Land/or recording instruzments containing threads of textile material as ianaessentialelement thereof.

1 Another objecttofthisfinvention'isthe applicaltio'nrin mechanical devices of dimensionally stable :texti-le' threads or high tenacity regenerated celludose'rprepared'by stretchingand then sapon'iiying rfilamen-ts or 'yarnswhaving a basis of cellulose acetate :or rothernorganicester of cellulose.

'aiOfther obj ects. of this inventionwill appear from the tollowingrdetd-iled description. and the accom- :panying drawing,

TI-nithe: construction of many types of instrumentsior-lother mechanical indicatingrdevices of a z'hig-h'rjdegree OfTDI'eClSlOIljflEXiblG threads of a tex- :ti'lematen'al form-essential elements thereof. For -a :high corder of accuracy and a precision -the .irthreads' nmst :possess "a high degree of -:dimenision'al stability. .-Any"change"in length, i. e; contraction .orrelongationfduring'variations of temperature and? humidityiimust be eliminated. In "instruments :..heretofore temployed, -threads 'of .various 1 textile :materials such as; for example, rcotton, :silk, nor synthetic: "linear polyamide condensationrproducts have been employed. Such threads': however, :do-not IPOSSBSS thedegree of dimensional-stabilityt during "variations of temperature andhumiditynecessary toobtain the re- :qnirdcaccuracy. "Since the oven-all precision of .lihosezin'struments ocontaining'zsuch threads can zba'no greatertlran thet'degreeof dimensional sta- --bil:ity: of thesiridividual threads employed, 'it is 'of .ntmostim-portance that threads of maximum "diimensionalstabi'lityibe employed.

felI''have nowzdiscoveredzthat precision a-instrumentszean'd indicating Z'dEViCGS 'Of' extreme accuracy, in which threadsform:.aneessentialelement, may now be constructed if the threads employed in said devices comprise high tenacity regenerlatedricelluloseyarns: having; a ba'sisof stretched and?saponifiedscellulose'. acetate :"or other organic :acid ester-ofrcellulosexrnaterial. Threads formed (ofxthese regenerated cellulose yarns are' OflIDlO- 'snounced sidimensional "stability, Preferably, :the

regenerated threads which I employ "are those X1111? whichf 'the elongation characteristics are such that the'ichangesiri lengthissno greater tharii3'% :overta'pvariationin humidity of from 10 to 100% and no'greaterthan 0.5% over a temperature variation from "50 to C.

"The cellulose acetate or other organic ester'tof celluloseyarnsor threads which are "stretched and then saponified to yield the regeneratedcellulosezyarns or threadsemployed in the devices of "mydnvention': may be prepared by extrudingiza solution of cellulose acetate or other organic'e'ster of "cellulose; dissolved in a suitable volatile -'.'solvent; through'a pluralityof orifices into an evaporative medium'as in the'dry methodof spinning, T01 xinto; acoagulating or precipitating liquid" mei'd-iumgeasin the wet-method of spinning. The filaments' formed in this manner are associated to- :gether to form the desired multi-filament yarni'or thread. .In :addition to cellulose acetateyother :organic'esters ofrcellulose'which may be employed for. thesprepa-ration of the dimensionally stable regenerated cellulose yarns are, for example-cellulose-*propionate; cellulose butyrate and mixed -esters'-tsuch' ias cellulose acetate-propionate and cellulose acetatebutyrate.

:After the yarn or. thread is formed, it is then stretched. This is'usually'done when the yarn .is"inra--'somewhat softened condition. 'The 'yarn cmay besoftened by treating it with a solvent, latentrsolventpor swelling agent for the cellulose acetate orfother'organic ester of cellulose. This softening: treatment may be carried out by'bat'h *orrpadding methods, or by exposing'the. cellulose acetate materials "to' vapors of said' organicsol- "vents; latent solvents or swelling agents during, or "just" prior? to, the stretching operation. "The 'yarns'may also besoftened by radiant heat-or by the use of i steam or hot*'water. After softening, .wtheyarns' may bestretched in acontinuousmananer bycb'eingpassedfrom a roll whichrotatesiat alow"speed to'one'rotating at a higher speedfthe :rollen rotating'at a higher speed serving togive the yarn "the desired stretch. The degree-50f :stretchrmayj be'varied by increasing or'decreas- .in'gz'the differentialin the speeds of'tharollers. .Theuyarnmay be stretched in a plura-lity of stages. :Forrexample, partof 'thestretch may be :imparted to'the yarn :by softening and stretching in one stage-and the remainder of--the stretch may-"be imparted'wby a second sof-teningiand :stretchingv-operation. More than two stages-of stretch may, of course, be employed. 'i-After stretching; the yarns may be taken upon -bobbins or may be collectedtin. a'centrifugal spinnin'g'box or Topham box.

By stretching the yarns, as described, the latter maysbeincreased in ilengthto the extent of 200, 300, 500 or even 1000 to 2000% of their original length. Preferably, the yarns employed in accordance with my invention are stretched at least 1000% or more. The stretching causes the cellulose acetate or other cellulose ester yarn or thread to acquire a relatively high tenacity and great resistance to further stretching. This increased tenacity is retained and frequently enhanced upon saponification. After the yarns or threads have been saponified and the regenerated cellulose yarns or threads obtained, the latter may then be employed in forming the threads which are incorporated in the measuring or indicating devices produced in accordance with this invention.

The cellulose acetate or other organic ester of cellulose yarns or threads which are stretched and saponified in the preparation of the regenerated cellulose yarns or threads may be of any degree of esterification. For example, in the case of cellulose acetate materials, they may have an acetyl value of from 40 to 62%, calculated as acetic acid.

The yarns may be saponified by batch processes or in a continuous manner. When a continuous process is employed the stretched yarns may be led directly into a saponifying bath, the path through the saponifying bath being sufficiently extended so that the yarn is completely saponified before leaving the bath. After saponification the yarn is washed free of the saponifying agent, dried and wound into packages of convenient size.

The saponification may be carried out by means of any suitable basic agent, The saponifying agent may be inorganic in nature such as, for example sodium hydroxide, potassium hydroxide, sodium silicate, ammonium hydroxide, sodium carbonate or other inorganic basic agent. Organic saponifying agents may also be employed such as, for example, methyl amine, ethylene diamine, triethanolamine or other organic bases. The saponifying agent may be employed in varying concentrations in aqueous, alcoholic or aqueous-alcoholic solutions. The saponifying bath may be at a temperature of 20 to 100 C. For example, when aqueous solutions of sodium hydroxide are employed, they may be of a concentration of 0.1 to by weight and saponification may be effected in from 30 to 180 minutes with the solution at 30 to 90 C. When employing aqueous solutions of sodium hydroxide as the saponifying medium, it is preferable to include a salt such as sodium sulfate or sodium acetate in said solution.

The threads employed in accordance with my invention may contain from to 500 or more filaments and have a total denier of from 30 to 1000 or more depending upon the particular device in which they are to be incorporated and the type of service they are to be subjected to. Not only single yarns but also plied yarns may be employed. When plied yarns are employed to form the threads, the latter may comprise 2, 3 or even more plies. The denier per filament in the yarn or thread may vary quite considerably. I prefer, however, to use filaments of a denier of from 0.2 to 2.0 in forming the improved regenerated cellulose yarns or threads. The plied yarns may have a twist therein of from 1 to 30 or more turns per inch of S-twist or Z-twist, and the plied yarn may have a twist of from 5 to 20 or more turns per inch of either S-twist or Z-twist.

In order further to illustrate my invention the following examples are given:

Example I A 90 filament cellulose acetate thread of 600 denier is softened, stretched to 10 times its original length and saponified at 60 C. with a 0.5% solution of sodium hydroxide containing 8% of sodium acetate. 3 ends of the 60 denier regenerated cellulose yarn obtained are plied together to form a thread of a total denier of 180. The single yarns contain 23 turns per inch of S-twist. The plied yarn is formed by plying the twisted individual ends and giving the plied yarn 17 turns per inch of Z-twist. This thread has a maximum elongation of 0.3% with a variation in relative humidity from 10 to 100% and of 0.5% with a temperature change of from 50 to C. The thread may then be incorporated as an essential element of a precision indicating device as illustrated, for example, by the accompanying drawing wherein a pressure sensitive indicating device is shown.

Referring now to the drawing in which an aneroid barometer designed to indicate a degree of change from any particular pressure condition is shown, the instrument comprises a base board l carrying a bracket 2 on which is mounted a sealed, evacuated chamber 3. One face of sealed chamber 3 comprises a diaphragm 4 having fixed thereto an eye 5. Fastened to eye 5 and responsive to any horizontal movement thereof is the plied regenerated cellulose thread 6 of high dimensional stability. From eye 5 thread 6 is passed around a rotatable shaft 1, several turns being taken, and then suitably fixed in a hole 8 passing through the shaft. Shaft I is mounted in roller bearings 9 which are carried in a bracket l0 fastened to baseboard I Shaft 1 carries at one end thereof an indicating pointer I I set in a collar 12 rotatably mounted on shaft 1 and adapted to be fixed thereon in any radial position as by suitable locking means (not shown). Pointer l 1 cooperates With a scale I3 graduated in suitable units and fixed to a circular mount I 4 fastened to base 1 as by a bracket I5. Pointer ll may be set at the zero point of the scale, as shown.

Any variation in barometric pressure causes diaphragm 4 to move in a horizontal direction due to the increase or decrease in the volume of evacuated chamber 3. This horizontal movement is transmitted through eyelet 5 to thread 6 which in turn causes a radial motion of shaft 1. This radial motion is amplified by the indicating pointer I l the variation in pressure being observed by reading the movement of pointer II on scale l3. Shaft 1 may be provided with a suitable calibrated hair spring 1, anchored at one end in a post 1" mounted on the inner face of circular mount [4 with the other end being set in shaft 1, to prevent any rotation of shaft 1 without a corresponding movement of diaphragm 4, eyelet 5 and thread 6. The extreme dimensional stability of thread 5 permits the accurate transmission of the movement of eye 5 to indicator H over wide extremes of both temperature and humidity and, consequently, devices containing said regenerated cellulose threads require no calibration or adjustment because of variations in external temperature or humidity conditions.

Example II The thread described in Example I may be replaced with a regenerated cellulose thread comprising 3 ends of a 120 filament, denier yarn of 19 turns per inch S-twist plied to form a single thread of 13.4 turns per inch Z-twist. Extremely satisfactory results may be obtained. I

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of my invention.

Having described my invention, what I desire to secure by Letters Patent is:

1. In a precision measuring instrument having a condition responsive device, an indicator and a motion transmission tensioned cable forming a connection therebetween, said tensioned cable comprising a high tenacity, dimensionally stable regenerated cellulose thread, said thread comprising stretched and saponified continuous filaments having a basis of an organic ester of cellulose, and having an elongation no greater than 0.3% over a variation in relative humidity of to 100%.

2. In a precision measuring instrument having a condition responsive device, an indicator and. a motion transmission tensioned cable forming a connection therebetween, said tensioned cable comprising a high tenacity, dimensionally stable regenerated cellulose thread, said ithread comprising stretched and saponified continuous filaments having a basis of cellulose acetate, and having an elongation no greater than 0.3% over a variation in relative humidity of 10 to 100% and an elongation of no greater than 0.5% over a temperature variation of -50 to +80 C.

3. In an aneroid barometer comprising an evacuated chamber provided with a flexible diaphragm adapted to move on variation in external pressure and indicating means responsive to the motion of said diaphragm, a thread intermediate of said diaphragm and said indicating means adapted to transmit the diaphragm movement to said indicating means, said thread comprising a high tenacity, dimensionally stable regenerated cellulose thread of stretched and saponifled continuous filaments having a basis of an organic ester of cellulose, and having an elongation no greater than 0.3% over a variation in relative humidity of 10 to 100%.

4. In an aneroid barometer comprising an evacuated chamber provided with a flexible diaphragm adapted to move on variation in external pressure and indicating means responsive to the motion of said diaphragm, a thread intermediate of said diaphragm and said indicating means adapted to transmit the diaphragm movement to said indicating means, said thread comprising a high tenacity, dimensionally stable regenerated cellulose thread of stretched and saponified continuous filaments having a basis of an organic ester of cellulose, and having an elongation no greater than 0.3% over a variation in relative humidity of 10 to 100% and an elongation of no greater than 0.5% over a temperature variation of from to C.

WILLIAM WHITEHEAD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,377,032 Starling et a1. May 3, 1921 1,848,053 Bacon Mar. 1, 1932 1,866,660 Luckey et a1. July 12, 1932 2,142,120 Dreyfus et a1 Jan. 3, 1939 2,311,900 Newell Feb. 23, 1943 2,364,135 Finlayson Dec. 5, 1944 

